Story: Gold and gold mining

Page 5 – Coromandel Peninsula

Payable gold

The first rumours of gold in New Zealand came from the
Coromandel Peninsula in the 1820s. Nothing came of the
reports for decades. Then in 1852 some Aucklanders offered a
reward of £100 for the discovery of a payable goldfield near
Auckland. When the reward was increased to £500, a sawmiller
named Charles Ring claimed it after he found golden flakes in
his pan at Driving Creek, near Coromandel town. His find led
to only a small patch of alluvial gold – by April 1853 less
than £1,200 worth had been won. But even a small strike
attracts prospectors, and if the original strike fails they
search again. Prospectors found little until quartz reefs
were uncovered in the hills of Coromandel Peninsula in the
early 1860s. But extracting gold from quartz was
difficult.

Hard rock at Thames

The first big strike was near Thames in August 1867, when
a speck of gold was seen in the rock face of a waterfall in
Kuranui Stream. Other reefs were uncovered, and within months
the Thames foothills swarmed with men. Mining quartz reefs
needed capital investment to tunnel, mine the ore, crush it
and separate the gold. This type of mining favoured larger
companies and gradually they took control of production.

Some reefs were spectacularly wealthy. In 1870 the
Caledonian mine in just over a year produced 140,000 ounces
(3,969 kilograms) of bullion (silver and gold). At the peak
of the rush in 1868, 18,000 people were living in Thames.
Other very rich reefs were soon discovered and quickly worked
out so that by the 1890s the big gold rushes were over.
Miners now knew where the gold was, but they needed to find
an economic way to mine it.

Recovering the gold

Machines called stamper batteries, which crushed quartz
into powder, were set up in the Coromandel ranges. Most mines
were steadily producing ore, but the recovery methods were
highly inefficient (only 45% of the gold and barely any
silver was recovered).

In 1889 the cyanide process was trialled by the New
Zealand Crown Mines Company at Karangahake – the first time
in the world cyanide had been used on a large scale for
commercial mining. Cyanide was added to crushed quartz ore.
Gold and silver dissolve in cyanide, allowing more of these
metals to be recovered (about 90% of gold and 50% of silver).
They are extracted from the cyanide solution using chemical
processes.

The new process was a leap forward as it made lower-grade
deposits profitable. Previously, much fine gold had been
lost, and in places it paid to rework tailings (waste rock)
with cyanide to recover the lost gold. Cyanide recovery
stimulated investment. Mining continued successfully until
the 1920s, by which time many ore reserves were depleted. The
depression saw a brief flurry of new mines but nothing came
of them.

A handful of very rich mines dominated production. One was
the Martha mine at Waihī, which when it closed in 1952 had
produced a total of 992,233 kilograms of bullion. Waihī was
the site of a large miners’ strike in 1912 – a bitter wrangle
that lasted six months and resulted in New Zealand’s first
death in an industrial dispute.

In the late 1960s the Tui mine at Te Aroha and the
Ohinemuri gold and silver mine at Maratoto reopened. They did
not last. Both closed in the 1970s after producing a further
5,018 kilograms of mainly silver, and some gold.